This invention relates generally to wiring systems for internal combustion engines. More particularly, this invention relates to wire guides for electronically controlled fuel injection systems in diesel engines.
Many diesel engines have hydraulically-activated electronically-controlled unit injection (HEUI) fuel systems. In these systems, each injector has a solenoid for activating a poppet valve. The poppet valve regulates the flow of high pressure oil in the injector. The high pressure oil controls the fuel injection into the cylinder.
The engine""s electronic control module transmits electrical signals to the solenoid via a connector in the valve cover. The connector also may be in the valve cover gasket, a valve fence, or part of the cylinder head. Under the valve cover, wires usually complete the circuit for transmitting signals from the electronic control module to the solenoids.
Generally, a pair of wires runs from the connector to each fuel injector. The pair of wires usually has a plug or a wire pigtail for connecting to the solenoid. The wires are positioned under the valve cover to avoid interference or entanglements with the rocker arms, valve rotators, and other moving parts. There may also be more than one pair of wires running from the connector to each fuel injector. Also, multiple connectors may be used to properly position the wires.
In a typical configuration, the connector is positioned between two fuel injectors. The connector may be placed on either the inboard or outboard side of the valve cover. From the connectors, wires run somewhat parallel to the valve cover before making almost perpendicular turns toward the fuel injectors to connect with the solenoids. In this manner, the wires avoid the rocker arms and other moving parts.
As alternatives to having wires under the valve cover, the wires or other types of conductors may be incorporated into the cylinder head, valve cover, or other parts. In one approach, the injectors are connected to electronics in or along the fuel rail. In a second approach, the wires are integral with the valve cover. The wires emerge underneath the valve cover at specific points for connecting to a particular injector. The wires emerge outside the valve cover to connect with the electronic control module. In a third approach, the wires lie along the inside surface of the valve cover. These wires have plugs at appropriate positions for connecting to the injectors when the valve cover is installed.
In other alternatives, the wires may be kept separated from the other parts underneath the valve cover. In one approach, wires are enclosed in a box or channel mounted on the fuel injection assembly. In a second approach, conductors are mounted in a connector block, which is mounted above the injectors. In a third approach, the wires are suspended on clips to keep the wiring above the injectors and other engine parts.
While these alternatives may provide suitable connections from the electronic control module to the injectors, they increase manufacturing costs and the assembly time of the engine. For example, incorporating the wires with the valve cover, fuel rail, or other engine parts increases the cost of those parts. It also increases the adverse impact of part failures. If the wire inside the valve cover or fuel rail does not operate, the valve cover or fuel rail must be replaced. This problem also increases maintenance costs because a new valve cover or fuel rail would be needed rather than replacement of a troublesome wire.
These alternatives also make assembly of the engine difficult. The plugs or connections on a valve cover or fuel rail must be aligned with the injectors before the cover or rail is secured in place. In some cases, it may be impossible to make the connections unless the wires have sufficient length. This xe2x80x9cextraxe2x80x9d length would be stored under the valve cover.
In addition, separating wires from other parts increases the space required under the valve cover. The height and width of the cylinder head and valve cover have to increase to accommodate a box or channel for the wires. Alternatively, a valve fence could be used, but it would increase the number of parts required. The height also has to increase for wires suspended on a clip above the injectors.
In comparison to the alternatives, wires routed in the available spaces underneath the valve cover make an engine easier to manufacture and cost less. However, using wires underneath the valve cover is difficult in a new HEUI fuel system. Improvements in HEUI fuel systems use fuel injectors with multiple solenoids. Usually, there are two solenoids on opposite sides of the injector. The solenoids control a spool valve in the injector. Each solenoid requires its own pair of wires (or a single wire if an alternate ground connection is used).
As opposed to facing the rocker arms, the fuel injectors are installed with one solenoid facing the side of the valve cover or fence. The other solenoid faces the valve rotators. One pair of wires runs somewhat parallel to the valve cover before making an almost perpendicular turn toward the fuel injector to connect with the solenoid. The wires have a straightforward run between the rocker arms. However, to reach the solenoid on the other side of the injector, the other pair of wires must cross the rocker arms or curve dangerously around the valve rotators. In either position, these wires interfere with or become entangled in the moving parts.
Going over the injector top is not an option. The high pressure oil rail sits upon and spans the top of the injectors. While wires may be routed on top or along the oil rail, they need to be secured in some manner so as not to move during engine operation. Tie bands and other securing means may be used. However, they increase manufacturing time and may not keep the wires from moving along the oil rail as the engine vibrates.
Accordingly, there is a need for guiding wires underneath the valve cover of a diesel engine so the wires do not interfere or become entangled with moving parts.
The present invention provides a wire guide for guiding and protecting wires from moving parts underneath the valve cover in a diesel engine. The wire guide has a channel portion connected to a base. The channel portion is configured to cross a rocker arm when the wire guide is mounted on the cylinder head.
The base has a main support connected to a side support and a foot section. A pedestal extends from the foot section to assist mounting on the cylinder head. The foot section and pedestal form a bore for securing the wire guide to the cylinder head with a bolt.
The channel portion creates a conduit for holding the wires. The conduit is essentially closed on two sides and partially closed on the bottom side, which has alternating cross-supports and open spaces, or simply intermittently spaced cross-supports. The top side is an open side, but constrained intermittently by pairs of retaining tabs.
The retaining tabs form along the top of the channel portion. They each have a tapered face, which has an upper edge and a lower edge. The upper edge helps to form the top side of the channel portion. The lower edge helps define the conduit. In a pair of retaining taps, the distance between the lower edges is less then the distance between the upper edges. This configuration creates an inverted wedge-shaped opening between the retaining tabs. Tapered faces and a wedged-shaped opening make it easier to push and retain wires in the conduit. In an alternate embodiment, the base is comprised of a retaining clip section that extends away from a side of the channel portion to assist in mounting the channel guide to the cylinder head. The retaining clip section is comprised of two prongs forming a snap-on assembly that xe2x80x9csnapsxe2x80x9d onto the injector clamp that holds the injector in place. The snap-on assembly secures the wire guide to the cylinder head.
In this embodiment, the conduit may be partially or completely closed on three sides. There is an open fourth side that is constrained intermittently by alternating and opposing retaining tabs. The retaining tabs form along the open side of the channel portion in an alternating and opposing fashion creating a series of alternating retaining tabs and open spaces along the channel portion. In use, the wires from the connectors pass through the wire guide. The wire guide crosses the rocker arms thereby keeping the wires from interfering and becoming entangled in the rocker arms and other moving parts.
The following drawings and description set forth additional advantages and benefits of the invention. More advantages and benefits are obvious from the description and may be learned by practice of the invention.